Fotodiox Pro Geared Follow Focus Drive for DV HDV DSLR, Fits Shoulder Supports, Stabilizers and Video Rigs - Premium Precision, Fits all 15mm Rod Mounts, Camera Reversible Completely gear-driven design for slip-free, accurate, and repeatable focus movement Fits Industry-standard 15mm (60mm spacing) rod mounts 1:1 gear ratio allows smooth movements for still and motion picture 35mm lenses Adjustable sliding mechanism to fit large range of lens diameters, including video camera lenses Gear drive can be mounted from both sides for left or right hand users